Electronic cooking apparatus

ABSTRACT

Cooking apparatus having a high frequency energy generator made as a magnetron. Cool air is taken into the apparatus along a flow path in which the cool air cools the magnetron and is thus heated. The heated air is applied as a hot air flow directly on to and generally parallel with a major inner surface of an inspection window on the apparatus. The air flow first contacts the window and then flows through and across the cooking compartment of the apparatus thus to eliminate formation of condensation on the window and splatter from reaching the window as food is cooked in the apparatus. Provision is made to eliminate leakage of high frequency energy or ratiation through the window by use of a shield that allows development of the hot air flow over the inner surface of the window.

United States Patent Suzuki et al.

ELECTRONIC COOKING APPARATUS Inventors: Masataka Suzuki; Minoru Shibata,

both of Shizuoka, Japan Assignee: Mitsubishi Denki Kabushiki Kaisha,

Tokyo, Japan Filed: Oct. 16, 1970 Appl. No.: 81,403

[30] Foreign Application Priority Data Oct. 23, 1969 Japan ..44/l00839 Oct. 27, 1969 Japan ..44/10l865 US. Cl ..219/l0.55, 126/190 Int. Cl. ..H05b 9/06 Field of Search ..2l9/l0.55; 126/193, 190

[56] References Cited UNITED STATES PATENTS 2/1970 Statts et a]. ..219/10.55 3/1964 Kellough et al ..219/10.55

3,177,334 4/1965 Kinkle ..2l9/10.55

[151 3,681,557 [451 Aug. 1, 1972 3,440,385 4/1969 Smith ..2l9/l0.55

Primary Examiner-J. V. Truhe Assistant Examiner-Hugh D. Jaeger Attorney-Robert E. Burns andEmmanuel J. Lobato 57 I ABSTRACT Cooking apparatus having a high frequency energy generator made as a magnetron. Cool air is taken into the apparatus along a flow path in which the cool air cools the magnetron and is thus heated. The heated air is applied as a hot air flow directly on to and generally parallel with a major inner surface of an inspection window on the apparatus. The air flow first contacts the window and then flows through and across the cooking compartment of the apparatus thus to eliminate formation of condensation on the window and splatter from reaching the window as food is cooked in the apparatus. Provision is made to eliminate leakage of high frequency energy or ratiation through the window by use of a shield that allows development of the hot air flow over the inner surface of the window.

, 7 Claims, 5 Drawing Figures BACKGROUND OF THE INVENTION This invention relates to an improvement in electronic cooking devices and more particularly to means for preventing an observation window of a door of the electronic cooking device from being fogged by aqueous particles such as vapor and/or oily and fatty particles dispersed from food being cooked and heated.

Generally, it is well known to equip a door of an electronic cooking device with an observation window for viewing into a heating compartment through such a perforated metal plate preventing excessive leakage of high frequency energy from the heating compartment and allowing a food to be well observed during cooking and heating. However, if only a perforated metal plate is provided for an observation window, comparatively hot ingredients such as oily and fatty particles dispersed from the food being heated are apt to run out of the cooking device through small diameter holes or perforations in the metal plate. Such dispersion of the hot ingredients is very dangerous for the user. In addition, the oily and fatty particles and refuses of the food are apt to adhere to the surfaces of the perforations and therefore, in such case, it is very troublesome to clean the perforations and the cooking device is apt to become fouled.

Furthermore, it is also well known to provide a transparent plate of colorless or faint color on the internal and/or other side of the perforated metal plate to overcome the above disadvantages. However, there is still a disadvantage that, in heating and cooking the food with the cooking device of that type, the transparent plate is fogged with condensation particles generated from the food, resulting in a bad visibility of the transparent plate when the cooking or heating .takes place when the transparent plate is cold and comparatively lower in temperature than the dew point temperature of the air having an aqueous content.

SUMMARY OF THE INVENTION Accordingly it is an object of the invention to eliminate the disadvantages of the prior art by the provision of an electronic cooking device in which a transparent plate arranged with a perforated metal plate is provided upon its internal surface with hot air developed when cooling a magnetron to thereby raise the temperature of the transparent plate to prevent the internal surface of the transparent plate from being fogged with condensation from the vapor generated from food being cooked.

It is yet another object of the invention to provide an electronic cooking device of the construction described in the preceding paragraph wherein the hot air forms a thin air film between the transparent plate and a heating compartment thereby preventing the oily and fatty particles dispersed from the food from reaching the transparent plate.

It is another object of the invention to provide an electronic cooking device of the construction described in the preceding paragraph wherein one side of the observation window facing toward the exterior of the cooking device is closed with a perforated metal plate and the other side facing toward the interior of the heating compartment is closed with a transparent plate detachably connected thereto thereby to render the flight of the oily and fatty particles from the food to be fully shut off by the transparent plate, allowing the particles adhered to the transparent plate to be capable of being removed with ease in cleaning the device.

It is still another object of the invention to provide an electronic. cooking device of the construction described in the preceding paragraph wherein the opening of the observation window facing opposite the heating or cooking compartment is closed with a perforated metal plate and the other side of opening facing toward the exterior of the cooking device has fitted therein a transparent plate with a plurality of air-vent holes through which the hot air can be discharged immediately after having blown against the internal 'surface of the transparent plate. A

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED I EMBODIMENTS Referring now to FIG. 1 of the drawing, it is seen that an electronic cooking device disclosed herein comprises a housing 8, a heating compartment 1 disposed within the housing 8 and including an opening on the front face or the lefthand face as viewed in FIG.- lJAn openable door 2 (with a handle 12) is pivotably mounted at the lower end as viewed in FIG. 1 to the front face of the housing 8, and a source 7 for generating high frequency energy, such as a magnetron, is

disposed on the outer surface of the upper wall of the heating compartment 1 and has a high frequency antenna 13 shown as projecting into the compartment 1. The door 2 is formed with an observation window 3 for viewing into the compartment 1 without opening the door 2. The outer opening of the observation window 3 facing toward the exterior of the cooking device is closed with a metal plate 4 with a plurality of small diameter perforations 4a whereas the inner opening of the observation window 3 facing toward the interior of the heating compartment 1 is closed with a transparent plate 5 made of such material, for example, as heat resisting plastic and glass. The high frequency energy emanating from the magnetron 7 is irradiated in a well known manner into the heating compartment 1 through the antenna 13 projecting into the compartment 1.-

A partition 14 having electromagnetic wave permeability, which is attached to the inner face of the upper wall of the compartment 1 as to be located under the antenna 13, is formed with an air outlet 15 near to the opening of the heating compartment 1. The air outlet 15 may be of rectangular shape in section and is provided along its peripheral edge with guide plates 16 for guiding hot air 10a to be blown against the inner surface of the transparent plate 5. A blower 10 forces a fresh air flow 10b to flow through the magnetron 7 for the purpose of cooling, and heat energy extracted from the magnetron 7 is absorbed by the air 10b from the blower 10. Thus,'the air 10b is rised in temperature and made to flow through a flow of air outlet 15 as the hot air 10a.

In operation, upon energization of the magnetron 7, the blower 10 is simultaneously rendered operative to cool the magnetron 7. The blower 10 draws in the fresh air 10b through an air inlet 9 provided in the lower wall of the housing 8 and forces it to flow through a path 20 formed between the compartment 1 and the housing 8 to the magnetron 7. Therefore, the incoming cool air cools the magnetron 7 while at the same time absorbing thermal energy from the magnetron 7, thus developing the hot air 10a. Then, the hot air 10a is forced to flow through a duct 11, an air outlet 17 provided in the duct 11, and openings provided in the upper wall of the compartment 1 to the air outlet 15 andhence oriented toward the transparent plate disposed on the inner side of the door 2 by the guide plates 16 provided along the peripheral edge of the air outlet 15 to be blown against the transparent plate 5, resulting in a rise of the temperature of the transparent plate 5. Thereafter, the

. hot' air is discharged externally as indicated by an arrow A through discharge ports 18 and 19 provided respectively in the upper wall of the heating compartment 1 and the back wall or righthand wall of the housing 8. It

is of course that each of the discharge ports 18 and 19 comprises a group of holes such as provided in a wire gauze having a comparatively small diameter sufficient to prevent the high frequency energy from leaking therethrough.

From the foregoing, it will be readily understood that, with the arrangement described above, the hot air absorbing the energy extracted from the magnetron is blown against the inner surface of the transparent plate so that the kinetic energy of the hot air is utilized to prevent the oily and fatty particles from the food being cooked from splashing on the transparent plate, and that the thermal energy of the hot air is consumed to elevate a temperature of the transparent plate thereby preventing the transparent plate from fogging with the vapor gnerated from the food, maintaining the observation window in a favorable condition of visibility.

In a modified arrangement shown in FIG. 2, the flow of the hot air a fed from the blower 10 through the magnetron 7 to the duct 1 l is further guided to the air outlet which is positioned substantially just above the transparent plate 5 and laterally extends along the transparent plate 5. Then, the hot air 10a is blown downwards along the inner surface of the transparent plate 5, thus forming a thin air film on the inner surface of the transparent plate. The air film thusly formed acts outer opening of the window has an area larger than that of the inner opening. It is therefore understood that the transparent plate 5 is larger in size than the perforated metal plate 4. As shown in FIG. 5, in the marginal portion projecting from the portion of the transparent plate 5 in which it faces opposite the perforated metal plate 4, there are provided a plurality of air-vent holes 6. With the arrangement shown in FIGS. 3-5, the hot air 10a from the blower 10 through the magnetron 7 and the outlets 15, 17 enters at the'holes 4a provided in the perforated metal, plate 4 and is blown upon the inner face of the transparent plate 5 to elevate its temperature and thereafter discharged out of the cooking device through the air-vent holes. 6. At this time, the oily and fatty particles dispersed from the food is fully shut off by the portion of the transparent plate 5 in which it faces opposite the perforated metal plate 4 as the air-escape holes 6 do not face opposite any one of the holes 4a provided in the perforated metal plate 4, so that the user is protected from being splashed with the oily and fatty particles.

While the invention has been illustrated and described in conjunction with a few preferred embodiments thereof, it is to be understood that various changes and modifications may be resorted to without departing from the spirit and scope of the invention.

What we claim is:

l. Acooking apparatus comprising, a housing having a cooking compartment therein, a high frequency generator in said housing for generating high frequency energy for cooking food in said compartment, means defining a transparent window on said casing for viewing into said cooking compartment during cooking of food in said compartment, means to reduce fogging of said window by formation of condensation 'on said window and splatter from food being cooked in said cooking compartment comprising means defining an air flow path in communication with the exterior of said casing for flowing air into the interior of said casing and over said high frequency generator to cool it, said means defining said flow path including means to discharge air heated upon cooling of said high frequency generator as a flow directly on and along a major inner surface of said window and generally parallel thereto, said cooking compartment having an exit spaced from said window for flow of said heated air flow outwardly thereof after contacting said window and subsequently flowing through said cooking compartment and outwardly thereof, driven means to draw air from exteriorly of said housing into said flow path and flow it positively over said high frequency generator to cool it and in direct contact with said inner surface of said window and subsequently through said cooking compartment to reduce fonnation of condensation therein and outwardly thereof exteriorly of said housing, and said exit being spaced from said window in a position in which the heated air flow flows across said cooking compartment in a direction away from said window inner surface.

2. A cooking apparatus according to claim 1, in which said driven means comprises a blower.

3. A cooking apparatus according to claim 1, including a pivotally mounted door on said housing for opening and closing said cooking department, and said means defining said window being disposed on said door, whereby when said door is Opened, said air flow protects the user of the apparatus from'steam, splatter and residual radiation.

4. A cooking apparatus according to claim 3, including a shield disposed spaced from and parallel to said 5 6. A cooking apparatus according to claim 1, including shield means internally of said casing and impervious to high frequency energy generated by said high frequency generator disposed to shield said window from said high frequency energy to preclude leakage therethrough exteriorly of said housing.

7. A cooking apparatus according to claim 1, including shield means impervious to high frequency energy generated by said high frequency generator disposed to preclude leakage of said energy through said exit and through said window. 7 

1. A cooking apparatus comprising, a housing having a cooking compartment therein, a high frequency generator in said housing for generating high frequency energy for cooking food in said compartment, means defining a transparent window on said casing for viewing into said cooking compartment during cooking of food in said compartment, means to reduce fogging of said window by formation of condensation on said window and splatter from food being cooked in said cooking compartment comprising means defining an air flow path in communication with the exterior of said casing for flowing air into the interior of said casing and over said high frequency generator to cool it, said means defining said flow path including means to discharge air heated upon cooling of said high frequency generator as a flow directly on and along a major inner surface of said window and generally parallel thereto, said cooking compartment having an exit spaced from said window for flow of said heated air flow outwardly thereof after contacting said window and subsequently flowing through said cooking compartment and outwardly thereof, driven means to draw air from exteriorly of said housing into said flow path and flow it positively over said high frequency generator to cool it and in direct contact with said inner surface of said window and subsequently through said cooking compartment to reduce formation of condensation therein and outwardly thereof exteriorly of said housing, and said exit being spaced from said window in a position in which the heated air flow flows across said cooking compartment in a direction away from said window inner surface.
 2. A cooking apparatus according to claim 1, in which said driven means comprises a blower.
 3. A cooking apparatus according to claim 1, including a pivotally mounted door on said housing for opening and closing said cooking department, and said means defining said window being disposed on said door, whereby when said door is opened, said air flow protects the user of the apparatus from steam, splatter and residual radiation.
 4. A cooking apparatus according to claim 3, including a shield disposed spaced from and parallel to said major surface of said window, said shield having openings thereon disposed for developing a flow of said heated air flow along said major surface parallel thereto and then flowing through said cooking compartment.
 5. A cooking apparatus according to claim 4, in which said shield is impervious to high frequency energy generated by said high frequency generator.
 6. A cooking apparatus according to claim 1, including shield means internally of said casing and impervious to high frequency energy generated by said high frequency generator disposed to shield said window from said high frequency energy to preclude leakage therethrough exteriorly of said housing.
 7. A cooking apparatus according to claim 1, including shield means impervious to high frequency energy generated by said high frequency generator disposed to preclude leakage of said energy through said exit and through said window. 